The present invention relates to a static pressure air surface stage or a float stage which is applied in superprecision measuring instruments, superprecision working machines, semiconductor manufacturing apparatuses requiring superprecision positioning operations.
Conventionally a static pressure air surface stage was described at page 207 of the thesis collection, Springtime Science Lecture Meeting, 1982 precision Machine Society.
As shown in FIG. 4 and FIG. 5, the surface stage is composed of a movable guide 3 which guides a stage 2 in a X-axis direction on a surface plate 1, a movable guide 4 which guides the stage 2 in a Y-axis direction, bearing pads 7, 7, 8, 8 disposed at both the ends of the respective movable guides 3, 4 and on the inner sides of the stationary guides 5, 6.
In the case of the conventional construction, reaction forces were applied upon the bearing pads 7, 8 because of the provision of the outer stationary guides 5, 6 through the blow-off operation of the compressed air from the bearing pads 7, 8. The movable guides 3, 4 were deflected because of the reaction forces of the bearing pads 7, 8, the reaction forces making it difficult to provide the better running precision of the stage 2.